1. Field of the Invention
The invention relates generally to systems and methods for transporting data and more particularly to systems and methods for conveying multiple low-bit-rate data streams over a data transport medium which is configured to transport data in a single, high-bit-rate data stream.
2. Background of the Invention
With the increasing computing power that is available for both commercial and private use, there is an increased demand for data transfer on a number of levels. Particularly, the emergence of the Internet and the ability of businesses and individuals to easily communicate with others around the world has created a need for greater speed, quality and capacity than ever before.
One response to the demand for increased performance in data transfers has been the development of optical data transfer systems. These systems use light instead of electrical signals to carry data from one point to another. Optical data transfer systems typically have much greater bandwidth than electrical systems of comparable size and cost, and are capable of providing higher quality signals for data transmission.
While optical data transfer systems provide advantages over electrical systems, they may also suffer from some drawbacks which may be found in any other rapidly developing technologies. Incremental advances in a technology may cause some previously developed hardware to become obsolete, or at least to have performance which is less than the greatest possible performance. Since it may nevertheless be cost-effective to implement a system using the out-of-date hardware, it is often necessary to enable the more advanced hardware to operate cooperatively with older hardware.
For example, a user may have a system which implements low-bit-rate data transfer paths, but may wish to utilize hardware which implements a high-bit-rate data transfer path. While the high-bit-rate data transfer path may be capable of handling low-bit-rate data transfers, this may leave a great deal of the available bandwidth unused. The user will have to pay for this bandwidth, whether it is used or not, so the incorporation of the more advanced technology may be impractical.
It would therefore be desirable to provide a means for making greater use of the hardware incorporating the advanced technology. Particularly, it would be desirable to provide a means for utilizing all of the bandwidth of high-bit-rate data transfer hardware when it is used in connection with equipment designed to transfer data at low bit rates.
Another problem is that systems which are currently available for optical-electrical conversion, transport and re-conversion may not be suitable for the needs of all users. These systems are typically designed to receive frames of data in a known format (e.g., SONET,) strip away the frame information, transport the data payload, add new frame information and deliver the newly framed data. While this is acceptable to some users, other users may desire a means for transporting an unaltered optical data stream from one point to another. That is, it may be desirable to maintain the proper bit sequence (the order of the bits within the data stream) as well as the rate at which the bits occur within the data stream. This may be true for a number of reasons. For example, the data stream may not be formatted according to the appropriate framing scheme, or it may be important to maintain the timing of the data between the transmitting and receiving devices. It is therefore desirable to provide a means for performing the conversion and transport of the data in a manner which is transparent to the user (i.e., it functions as a virtual fiber.)